1. Field of the Invention
Embodiments of the present invention relate to an evaporated fuel processing apparatus configured to process evaporated fuel generated in a fuel tank.
2. Description of the Related Art
For this type of apparatus, for example, there is proposed an apparatus provided with: a canister containing adsorbent for adsorbing evaporated fuel generated in a fuel tank; and a blocking valve with a stepping motor disposed in a vapor passage, which connects the canister and the fuel tank (refer to Japanese Patent Application Laid Open No. 2015-218659). Japanese Patent Application Laid Open No. 2015-218659 discloses that when step-out of the stepping motor is detected, initialization for moving the blocking valve to a predetermined initial position is performed at an initialization time, which is determined in advance as the best time for not adversely affecting engine operation.
A rotation amount (or rotation angle) of the stepping motor is controlled in a step unit. In the initialization of the blocking valve, in most cases, the stepping motor is rotated with a predetermined step number (i.e. a predetermined number of steps) in a valve closing direction, from a position at which the step number of the stepping motor is “0” (i.e. the initial position).
Such control is effective to certainly initialize the blocking valve when the position at which the step number of the stepping motor is “0” is shifted from a true initial position. If, however, the predetermined step number is set as a fixed value, the aforementioned control possibly accelerates deterioration of the blocking valve when the position at which the stepping number of the stepping motor is “0” is not shifted from the true initial position.